Conventionally, positioners have been provided in control valves, where the valve opening of the control valve is controlled by the positioner. This positioner has a calculating unit for calculating a deviation between a control valve opening setting value sent from a higher-level device and an actual opening value that is fed back from the control valve, to generate, as a control output, an electric signal in accordance with this deviation; an electro-pneumatic converting device for converting, into a pneumatic pressure signal, the control output generated by the calculating unit; and a pilot relay for amplifying the pneumatic pressure signal, converted by the electro-pneumatic converting device and outputting the result, as a pneumatic pressure signal, to an operating device for the control valve (See, for example, Japanese Unexamined Patent Application Publication S62-28118).
In this positioner, the pneumatic converting device and pilot relay each may be of a positive operating mode or a negative operating mode. That is, the positive operating mode is of an operating system of a nature wherein the greater the input, the greater the output will be, where, on the other hand, the negative operating mode is of an operating system having a nature wherein the greater the input, the smaller the output will be. Given this, the operating mode of the positioner itself depends on the forms of operation of the built-in electro-pneumatic converting device and pilot relay. That is, as illustrated in FIG. 12, if the modes of operation of the electro-pneumatic converting device and the pilot relay are identical, then the positioner is in the positive operating mode, but if the modes of operation of the electro-pneumatic converting device and of the pilot relay are opposite from each other, then the mode of operation of the positioner is in the negative. Furthermore, the type of positioner to use, in terms of the type of operating mode, is determined by the operating mode of the control valve wherein the opening is controlled by the positioner.
Here if, for example, a change is produced so as to control a control valve of the opposite operating mode from the control valve that has been controlled until that point, or if there is a failure in a positioner that has controlled the control valve, making it necessary to replace suddenly with a spare positioner, where this spare positioner and control valve are of different operating modes, then the operating mode of the positioner is changed through changing the operating mode of the built-in electro-pneumatic converting device through changing the direction of the electric current supplied to a magnetic excitation coil (See, for example, Japanese Unexamined Patent Application Publication H11-118526). Additionally, if the pilot relay that is built into the positioner is a multimode pilot relay (of a type wherein it is possible to select the positive operating mode or the negative operating mode), then the operating mode of the positioner can be changed by selecting the opposite operating mode from that which had been used up to that point.
Furthermore, in order to control the opening of the control valve in the positioner accurately when there is a change in the operating mode of the positioner, it is necessary to set the current operating mode of the positioner itself and of each parameter for control, and the setting of the current operating mode of the positioner itself and of the various parameters are performed artificially.
However, in the positioner there is a variety of parameters such as the proportional gain, the internal gain, the differential gain, and the like, as various parameters for control, and these parameters differ depending on whether the positioner is in the positive operating mode or the negative operating mode, and depending on whether the electro-pneumatic converting device and pilot relay are in the positive operating mode or negative operating mode, where the operation for changing the settings of the various parameters is extremely complex.
That is, there are four combinations of the operating mode of the electro-pneumatic converting device and the operating mode of the pilot relay, so even if the operating mode of the positioner is the positive operating mode, there is the case wherein the operating modes of the electro-pneumatic converting device and the pilot relay are both the positive operating mode, and the case wherein they are both the negative operating mode, and even if the operating mode of the positioner is the negative operating mode, there is the case wherein the electro-pneumatic converting device is in the positive operating mode and the pilot relay is in the negative operating mode, and the case wherein the electro-pneumatic converting device is in the negative operating mode and the pilot relay is in the positive operating mode, and in some cases there are small differences in the best parameters depending on these four combinations of operating modes, and thus the operations for updating the settings of the various parameters are extremely complex.
Additionally, if, for example, the operator forgets the operation for updating the setting of the current operating mode of the positioner itself or the settings of the various parameters, or if the operator was unable to update the settings of the various parameters accurately, then the operating mode of the positioner may not match the various operating parameters in the settings, which risks the occurrence of problems, not only with preventing the correct control of the opening, but also with causing failures in the system wherein the flow of the fluid is controlled by the control valve.
The present invention was created in order to solve the problem as set forth above, and the object thereof is to provide a positioner wherein it is possible to cause the current operating mode of the positioner and the various parameters for control to be set automatically.